05 fisiologia comp dig adapt digestivas.unlocked

7/28/2019 05 Fisiologia Comp Dig Adapt Digestivas.unlocked

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Digestive Adaptations toVarying Feed Sources? Gastric capacity and structure

? Capacity is greatest in pregastric

fermentors? Stomach acts as reservoir

?? Small stomach in carnivores is related to high nutrient density of the diet

?? Distribution and composition of epithelial lining varies between species and dietary

adaptations


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Digestive Adaptations to

Varying Feed Sources? Intestinal length and functions

? Small intestine

? Less variable among species than stomach and hind gut, but generally shorterin carnivores than in herbivores

? Large intestine

?Importance of hind gut fermentation dictates

variation in structure and size

? Some hind gut fermentation occurs in most

species


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Adaptations of the

Digestive Tracts

StomachSmall Intestine

Cecum

Large Intestine

Size = Function


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Adaptations of

Digestive Enzymes?? Young animals produce little sucrase, maltase, amylase

? Ruminants produce no sucrase

? Adult pigs lack lactase

? Activity changes with age? Lactase

? Sucrase, maltase


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Utilizing Cellulose? Advantages

? Ultra-abundant in the environment

? Easily obtained no need to hunt plants

? Plant cell walls & fiber high in

energy

? Disadvantages


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? Indigestible by mammalian digestive enzymes

?? Cellulase is found only in bacteria & some protozoans


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Fermentative Digestion?? All mammals have some fermentative capacity that allows for utilization of ingested

fiber

?? The comparative importance of fermentation is related to the fraction of total digestacontained in fermentative compartments of the gastrointestinal (GI) tract


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Advantages of PregastricFermentation

? Make better use of alternative nutrients

? Cellulose

? Nonprotein nitrogen

?? Ability to detoxify some poisonous compounds

? Oxalates, cyanide, alkaloids

?? More effective use of fermentation end- products

? Volatile fatty acids, microbial protein, B vitamins

? Allows wild animals to eat and run


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Disadvantages of PregastricFermentation

? Fermentation is inefficient

? Energy

? Loss % of total caloric value

Methane 5-8

Heat of fermentation 5-6

? Relative efficiency is dependent on the diet NDF

? Protein

? Some ammonia resulting from microbial degradation will be absorbed and

excreted

? 20% of the nitrogen in microbes is in theform

of nucleic acids


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Disadvantages of PregastricFermentation? Ruminants are susceptible t ketosis

? Ruminants are susceptibleby rumenmicrobes

? Nitrates to nitrites

? Urea to ammonia

? Nonstructural carbohydrates to lactic acid?Tryptophan to 3-methyl indole

? Isoflavonoid estrogens to estrogencoumestans


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Pregastric FermentersClass Species Dietary habit

Ruminants Cattle, sheep

Deer, antelope,

camel

Grazing herbivores

Selective herbivores,including

Nonruminants Colobine monkey,

hamster, vole

Kangaroo, hippo

Hoatzin

Selective herbivores

Grazing and selectiveherbivores


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Postgastric Fermentors? Cecal fermentors

? Mainly rodents, rabbits and other small herbivores

? Often associated with coprophagy

? Colonic fermentors

?? Includes true herbivores (e.g., horse), omnivores (e.g., pig and human), and carnivores(e.g., cat and dog)

? Horse has some expanded cecal fermentation in addition to greatly expanded

colonic fermentation

?? Degree of colonic sacculation is related to importance of fiber digestion andfermentative capacity


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Postgastric FermentersClass Speci Dietary habit

Cecal digesters Capybara

Rabbit

Rat, mouse

Grazer

Selective herbivores

Omnivores


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Colonicdigesters

Sacculated

Unsacculated

Elephant, horse,

zebra New Worldmonkeys Pig,

human

Panda

Grazers

FolivoresOmnivor

es

Herbivor

Foregut vs. HindgutFermentation

? Foregut

? More efficient per unit volume of food

? Slower digestive process

?

Animal may starve with a full belly

? Size restricted


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? Hindgut

? More efficient relative to time

? Faster turnover


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NONRUMINANT

HERBIVORE

Simple stornacn,

large cecum

RUMINANT

HERBIVORE

Four-chambered stomach

with large rumen; long

small and large intestina

Esopha

gus

Omasu

m

Anus


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Anus


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Feeding Habits of

Mammals& TaxonomicDistribution

Feeding Habit Number of Orders Percent of Species

? Herbivory 10 40

? Frugivory, Graniv., Nectivory 5 4

? Carnivory 4 12? (Kr feeder 2


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? Omnivory 7 10


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Classification of

Animals by

Preferred IngestedFeedstuffs

? Carnivore consume animal products

? dogs, cats? komodo dragon, tigers, eagles, sharks, polar

bear

? Herbivore consume plant products

? cattle, sheep, goats, horses

? giant panda, gorilla, elephant, ostrich,

green iguana, giraffe, American bison

? Omnivore plant and(or) animal products


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? pigs

? opossum, raccoon, blue jays, black bear,

human


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Specialized Carnivores

Aphidivore - feeds on aphids Apivore -feeds on bees Erucivore - feeds on

caterpillars Insectivore - feeds oninsects Larvivore - feeds on larvaeMyrmevore - feeds on ants Mucivore -


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feeds on flies Piscivore - feeds on fishPupivore - feeds on pupae Ranivore -feeds on frogs Sanguivore - feeds onblood Zoosuccivore - feeds on liquid

animal secretions of

decaying animal matter


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Specialized HerbivoresAmbivore - feeds on grasses and broad leaf plants Exudativore -feeds on gums, resins, and sap Folivore - feeds on foliage (leaves ortrees) Forbivore - feeds on forbs (i.e. flowering plants) Frugivore -feeds on fruit

Graminivore - feeds on grassesGranivore - feeds on grains

Gumivore - feeds on gums secreted by someplants


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Lignivore - feeds on woodMellivore - feeds on honeyNectarivore - feeds on nectar Nucivore -

feeds on nuts (agouti) Phytisuccivore - feeds

on (tree) sap Radicivore - feeds on roots


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Classification by Type ofDigestion or Site ofDigestion? Monogastrics or non-ruminants

? Ruminants

OR

? Pre-gastric fermentation (cranial)

? Post-gastric fermentation (caudal)


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Monogastric Animals? Single, simple stomach structure

? Mostly carnivores and omnivores

? Very simple - mink, cat and dog


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?? Cecal digestion - horse, rabbit, elephant or rat

? Sacculated stomach - kangaroo


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Ruminant Animals

?? Ruminant herbivores possessing multiple digestive tract compartments

for feed breakdown before feed

reachesthe true stomach? True ruminants - cattle, sheep, goats? Pseudo-ruminants - camels, llamas, alpacas,


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vicunas


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RumenFood chewed

several times

Rate of passage:A

80 hoursCelluJose

utilization

60%


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GIT Capacity - Volume? Carnivores? stomach (70%) > SI = LI (15%)? GIT surface/body surface: 0.6:1

? Omnivores

? stomach = SI = LI (33%)

? GIT surface/body surface: intermediate

? Herbivores

? Ruminants

? stomach (70%) > SI (20%) > LI (10%)

? GIT surface/body surface: 3:1

? Non-ruminants

? stomach (10%) < SI (30%) < LI (60%)

? GIT surface/body surface: 2:1


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GIT Classifications -Dog

?? Monogastric carnivore with limited post-gastricfermentation

?? Simple stomach, not capable of effectiveutilization of forage-based (high fiber) diets

?? Unable to digest some of the substances

in grains, fruits and vegetables

? Similar to cat


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GIT Classifications - Pig

?? Monogastric omnivore with limited post-gastricfermentation

?? Simple stomach, not capable of effectiveutilization of forage-based (high fiber) diets

?? Unable to digest some of the substances


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in grains, fruits and vegetables

? Similar to human


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Pig

Stomach

(2 gal)

Large Intestine

(16, 2 gal)

Esophagus


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Cecum

(10, 0.5 gal)

Small intestine

(60, 2.5 gal)

Mouth


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Human

Digestive Tract


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Rat


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GIT Classifications -Kangaroo

?? Monogastric omnivore with limitedpre-gastric fermentation

?? Sacculated stomach,capableof utilization of forage- based(high fiber) diets

?? Able to digest some of thesubstances in grains, fruitsand vegetables


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GIT Classifications -Horse?? Monogastric herbivore with

extensive post- gastricfermentation

?? Simple stomach incapable ofutilization of forage- based (high

fiber) diets

?? Extensive fermentation afterprimary sites of digestion andabsorption


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Hors

eSmall Colon (12, 3 gal)

Small intestine

(70, 12 gal)

Esophagus

Large Colon

(12, 19 gal)

Cecum

Mouth


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(4, 8 gal)

Stomach (3.5 gal)


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GIT Classifications -

Sheep?? Ruminant herbivore with extensive pre-gastric

fermentation

?? Highly developed sacculated stomach capable of

extensive and effective utilization of forage-based(high fiber) diets

?? Extensive fermentation before primary sites

of digestion and absorption

? Similar to cattle and goats


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Cow

Large intestine Esophagus(33, 8 gal)Cecum

(3, 3 gal) Rumen (paunch) (43 gal)

Mouth


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Small intestine

(150, 16 gal)

Abomasum

(glandular) (5 gal)

Omasum

(4 gal)

Reticulum

(honeycomb) (2.5 gal)


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GIT Classifications? Avian is modified monogastric


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? Beaks replace lips and teeth

? Crop (enlarged area of esophagus) stores and softens feed

prior to entering stomach? Proventriculus glandular stomach

? Gizzard muscular part of stomach

? Branched cecum postgastric fermentation

? Cloaca both fecal and urinary waste

? Uric acid rather than urea

(insoluble)


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Avians (Poultry)Mouth? No teeth, rigid tongue

? Poorly developed salivary glands

? Saliva contains amylase

? Beak is adapted for prehension and

mastication


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Avians (Poultry)

Esophagus

? Enlarged area called crop

? Ingesta holding and moistening

? Location for breakdown of carbohydrate by amylase

? Fermentation

Proventriculus (stomach)

? Release of HCl and pepsin (gastric juices)

? Ingesta passes through very quickly (14 seconds)


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Avians (Poultry)

Gizzard (ventriculus)

? Muscular area with a hardened lining

reduces particle size? Muscular contractions every 20-30 seconds? Includes action of grit

? HCl and pepsin secreted in proventriculus

Small intestine? Similar to other monogastrics

? No Lacteals


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Avians(Poultry)

Ceca and large intestine

? Contain two ceca instead of one as in other

monogastrics?? Large intestine is very short (2-4 in) and empties into cloaca where fecalmaterial will be voided via the vent

? Water resorption

? Fiber fermentation by bacteria

? H2

O soluble vitamin synthesis by bacteria

Chi k


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ChickenBeak

EsophagusCrop (2) SmallIntestine (55)

Proventriculus

Gizzard (2)Pancreas

Ceca (7)Large Intestine (4)

Cloaca


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Feeding Behaviors? Impact feed choices? Neophobia (avoidance of new feed sources)

? Contact testing (based on taste and other sensory

information collected in mouth) prior to swallowing

? Early introduction of a variety of feeds limits this problem

?? Chimpanzees select feeds based on easily digestible carbohydrate content(sugars and starches) rather than fat or protein content

?? Grazers and browser select early growth grasses and plants vs. mature growth

?? In confinement feeding situations, grazers consume concentrates first and then

forages in ration based on particle size (basis for creating total mixed rations)


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Feeding Behaviors


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?? Impact feed intake (avoiding under- and over-consumption of feed)

?? Hiding feed in bear exhibit encourages search and gather behaviors,limiting intake and reducing the stress of captivity

? Predator behavior towards prey

meals vs. bowl meals

?? Grazing animals prefer to eat forage at ground level rather than in


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elevated feed bunks

05 fisiologia comp dig adapt digestivas.unlocked

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